Means for the colloidal dispersion of materials



Nov. 13, 1945. A. R. TRIST 2,389,012

MEANS FOR THE COLLOIDAL DISPERSION OF MATERIALS Filed Dec. 50, 1942Patented Nov. 13, 1945 ATES ATENT OFFICE MEANS FOR THE COLLOIDALDISPERSION OF MATERIALS Arthur Ronald Trist, London W. 1, England 4Claims.

This invention relates to a new and improved process for the colloidaldispersion of materials and has for its object to produce a very largevariety of oil or water phase emulsions of great stability, in aneincient, practical and economical manner.

The invention contemplates the production of oil or water phaseemulsions in which the particle size can be less (when required) thanthat which occurs in nature made latex emulsions.

The invention also contemplates the use of novel, simple andcomparatively inexpensive devices of a character suited to industrialuse and which with the elements or units of the complete installation,form a novel combination, the constituent parts of which co-operate toapply the novel process in a practical way.

The invention further contemplates treatment in two stages, both ofwhich comply with the same theoretical basis, although the products aredissimilar in some respects.

Generically the invention is characterised in that colloidal dispersionof a high order is obtained in a liquid mixture, by applying kineticenergy under controlled pressure to create very active molecularturbulence accompanied by a controlled rise in temperature of theassociated materials, said materials being circulated through thekinetic energiser and the turbulence producing means until the particlesize is sumciently reduced and the excess of heat is more or lessabstracted.

When implemented, the circuit comprises a power operated pump, a flowimpediment or resistance, a heat interchanger and canalisation, but doesnot necessarily involve a sealed circuit; the only limitations beingthat the parts selected will produce the defined result.

To control performance a pressure gauge is located in the canalisationbetween the pump delivery and the flow impedance and in a general way,it may be assumed that the value of the impediment is such that nodifference of pressure exists in the heat exchanger,

As already stated, the process usually includes two stages, each ofwhich produces a different result, the second stage producing anemulsion, whilst the first stage produces a favorable predispersion ofcertain of the constituents of the emulsion The invention can be carriedinto practice by many dilierent mechanical constructions and thereforethe arrangement described and shown in the accompanying drawing must beregarded as by way of example only, and in order that the descriptionmay be understood reference will be had to the several figures of thedrawing and to the letters marked thereon, like letters referring tolike or similar parts in the different figures in which- Figure 1 showsschematically an arrangement for carrying out the first stage;

Figure 2 shows schematically an arrangement for carrying out the secondstage; and

Figure 3 is a sectional elevation of one kind of flow impediment orresistance suited to the improved process.

As shown in Figure 1 the arrangement of the predispersing means consistsof a pump a of any kind having a delivery pressure of about threehundred pounds per square inch and capable of imparting the requiredkinetic energy to the liquid being pumped, that is to say, the pump amay have a rotor or plungers but preferably should be a rotary impellertype of pump (turbo) inasmuch as such a pump has no valves or otherloose parts likely to introduce difiiculties.

The pump a is operated by the motor I), such for example as anelectromotor or a steam turbine, has its suction 0 connected to the tankd and delivers through the homogenising valve e.

The contents of the tank (1 usually have to be cooled and to that end ithas been shown in the form of a cone disposed within a cylindricalcasing f to which it is attached to form the water jacket g, butobviously any other form of heat exchanger of appropriate kind can beused. The tank d is not provided with a cover and receives the dischargefrom the valve e, the pipe connecting the pump a to the valve e having apressure gauge It so that the valve e can be adjusted to give therequired impediment.

The valve e as shown by way of example in Figure 3 consists of a body zhaving a discharge branch 7' and an internally threaded taper bore inwhich is located an externally threaded taper plug it. The plug k isprovided with a stem I at its upper part, passing through a stufiing boxm in the upper part of the body 2 adjacent to the discharge branch 7'and having an externally disposed hand wheel n thereon so that the plugis can be rotated in the body 2' to increase or decrease the impedimentby adjustment of the width of the helical passage between the threadsand to steady the lower end of the plug k, such end is provided with agrooved prolongation n which co-operates with the cylindrical bore 0 inthe inlet branch p of the said body 2.

As shown in Figure 2 the homogeniser or emulsifier consists of a pump a(having similar characteristicsto those of the pump a), a motor I) and aclosed chamber d connected to the suction c of the pump a.

The delivery of the pump a is connected to a homogenising valve e thedischarge d of which is connected, on the one hand, to a heatinterchanger coil q immersed in a suitable liquid contained in the tank1, and on the other hand, to

the upper part of the chamber d The discharge end of the coil q isconnected "to the upper part of the chamber d valves s and t controllingthe volume of the flows directly to the chamber d by the valve t andindirectly to the chamber (1 by the valve s through the coil q so thatthe temperature of the liquid in the chamber d can be maintained at anydesired level.

The chamber d has a closely fitting cover d which may be removed forcharging purposes, or in a large installation a door such as d may beprovided and further the chamber (1 is provided usually at its lowerpart, with a discharge spout u and cover 1).

To ensure that the sequentially treated liquid supplied to the chamber dis properly intermingled a stirring apparatus, such as w, may be housedin said chamber and operated for example by the pulley :r.

As in the case of the predispersing means a pressure gauge h is includedin the pipe carrying the discharge from the valve e in order that thevalve 2 may be adjusted to give the particular impediment required.

It will be understood that the valve e may be modified in a variety ofways; for example, the thread on the plug is may be mutilated, that isto say, be interrupted locally here and there, perhaps on alternatethreads; or the shape of the thread in the bore may be slightlydifferent to the shape of the thread on the plug, and it will beself-evident that the thread may be angular, circular, square, or ofbuttress shape so that materials of diiierent kinds and viscosity can behandled in a proper manner.

By way of example it may be assumed that a pigmented petroleum emulsionis to be produced.

In the first place, the petroleum, pigment, catv alyst, polymer, resinand so on, are placed in the tank cl and forced through the valve e bythe pump a back into the tank d, which by virtue of the waterjacket 9acts as a heat exchanger, the degree of generated heat and the zone ofactivity of the molecular turbulence due to the dissipation of kineticenergy being judged by the pressure generated whilst the reactions ofthe ingredients is provided for by the volume of the heat interchanger,which determines the length of the period of time during which thetemperature of the ingredients is being decreased or increased; usuallythe desired result is obtained with a pump discharge pressure of abouttwo to three hundred pounds per square inch, a deliv- 'ery pressure asshown by the gauge h of about one hundred pounds per square inch, adelivery temperature from the valve e of about one hundred to onehundred'and twenty Fahrenheit degrees, and a delivery temperature fromthe tank d of about sixty-five to seventy Fahrenheit degrees.

Sometimes improved results can be obtained by predispersing two or threeingredients together, and predispersing such mixture with-otheringredients, it being understood quite clearly that ultimately apredispersed mixture is obtained in which the maxima of chemical,physical and electronic reactions have taken place, all the particlesare predispersed colloidally and the size of the particles is as smallas desired at this stage.

Such a predispersed mixture is ready for actual emulsiflcation withwater, and for that purpose is introduced into the chamber 41 which isthen closed by the cover d, and the stirring apparatus w is set inmotion.

As already explained, the circuit in this stage of operation comprisesthe power operated pump a the homogenizing valve 1?, the heat exchangerq, the chamber d and valves s and t, by which the flow from the valve 6can be led directly to the chamber d or to the heat exchanger coil q,from whence it passes to the chamber d the periods of time during whichthe mixture is in the chamber (1 (being beaten or not) and in the heatexchanger coil q (being heated or cooled) I being determined by thevolume of the several units, and as before, neither the heat exchangercoil q nor the chamber 11 are under any appreciable rise in pressure.

By this arrangement of parts kinetic energy is applied to the mixtureand water under controlled pressure, as indicated by the gauge h, tocreate very active molecular turbulence. accompanied by a controlledrise in temperature of the associated materials whilst said materialsare circulating in a closed circuit which sometimes comprises: pump a,homogenizing valve 6, tank d, pump a and so on, and sometimes comprises:pump a homogenizing valve e, heat exchanger coil q, chamber (2 pump aand so on, the valves s and t controlling the dual flow directly and thethermal interchange indirectly.

Thisprocess of kinetic colloidalisation enables a very wide choice ofmaterials and the proportions thereof to be made, the polarity of thecharges on the particles to be controlled, and the particle size to bereduced with great ease; the implementation being'of such a simple kindthat it can be arranged without any difllculty to avoid loss ofvolatiles, thereby constituting a new method which can be practised bymeans of greater adaptability, and of simpler construction than knowncontrivances such as hydraulic homogenisers, colloid mills and suchlike.

I claim: I

1. Improved means for the colloidal dispersion of materials comprising aheat exchanger, a high speed pump receiving liquid from said exchangerand delivering said liquid to a homogenising valve consisting of a taperplug having a spiral thread, a threaded taper body co-operating withsaid threaded plug, means for rotating said plug to vary the width ofthe helical passage of constant breadth between the confines of thethread and means for conveying the discharge from said passage to saidexchanger.

2. Improved means for the colloidal dispersion of materials comprising aheat exchanger, a high speed pump receiving liquid from said exchangerand delivering said liquid to a homogenising valve consisting of a taperplug having aninterrupted spiral thread thereon, a threaded taper bodycooperating with said plug, meansior rotating said plug to vary thewidth of the helical passage of constant breadth between the confines ofthe thread and means for conveying the discharge from said passage tosaid exchanger.

3. Improved means for the colloidal dispersion of materials comprising ahigh speed delivery pump for imparting kinetic energy to said delivery,a threaded taper body co-operating adjustably with a taper plug having aspiral thread receiving said delivery and converting said kinetic plughaving a spiral thread for receiving said energised fluent mixture forconverting said kinetic energy into heat and for delivering a heatedfluent mixture without appreciable positive pressure, means forabstracting heat to cool the fluent mixture and means for feeding saidcooled fluent mixture to said kinetic energy imparting means to maintaina closed cycle of repeated treatment.

AR'IHUR RONALD 'I'RIST.

